The invention relates to a ballast apparatus for attaching to the rear of a crane superstructure, in particular of a crawler-mounted crane, having a base plate and a plurality of stackable ballast plates.
There is generally a risk of tilting for a machine such as a crawler-mounted crane which stands freely on the ground when the tilting torque caused by the effect of the load and the inherent weight becomes larger than the standing torque of the machine. The function of the rear ballast or of the ballast in general is the reduction or the compensation of the active tilting torque. The rear ballast in the crane is typically arranged at the rotatable upper part and in the opposite direction to the payload. In a crawler-mounted crane, the rear ballast has previously been arranged in a fixed position at the rear of the superstructure.
During crane operation, the forces and torques acting on the machine can vary abruptly, for example by an increase or decrease of the radius of the load. Fixed-position rear ballasts do not allow any flexible adaptation to the changed operating conditions. If e.g. the active tilting torque is increased by an increase in the working radius, the stability of the machine decreases since the compensating rear ballast torque remains constant due to the fixed-position location of the ballast with respect to the superstructure. Only a complex and/or expensive increase of the ballast weight by taking up further ballast plates provides a remedy.
The use of movable ballast apparatus is already known from the prior art. A solution for setting the rear ballast during crane operation is disclosed in EP 2 281 771 A1. Here, the rear ballast is horizontally displaced via a complex rail mechanism or telescopic mechanism, i.e. the ballast can either be moved closer to the crane superstructure or can alternatively be moved further away from it.
A similar variant is known from EP 2 657 176 A1 in which the rear ballast is distanced from the superstructure by a horizontal displacement and is additionally raised upward.
However, both solutions require a comparatively complex ballast actuation design.
With machines of small dimensions, the total machine width is typically defined by the rear ballast. When passing through narrow points on the construction site, it can therefore be necessary to dismantle the rear ballast, which unnecessarily increases the resulting equipping time and thus reduces the operation readiness of the machine. A solution of this problem which makes the complex and/or expensive dismantling superfluous is not yet known from the prior art.